#pragma once
#include<iostream>
#include<assert.h>
#include <time.h>
using namespace std;


template<class K, class V>
struct AVLTreeNode
{
	pair<K, V> _kv;
	AVLTreeNode<K, V>* _left;
	AVLTreeNode<K, V>* _right;
	AVLTreeNode<K, V>* _parent;
	int _bf; // balance factor

	AVLTreeNode(const pair<K, V>& kv)
		:_kv(kv)
		, _left(nullptr)
		, _right(nullptr)
		, _parent(nullptr)
		,_bf(0)
	{}
};

template<class K, class V>
class AVLTree
{
	typedef AVLTreeNode<K, V> Node;
public:
	AVLTree() = default;

	AVLTree(const AVLTree<K, V>& t)
	{
		_root = Copy(t._root);
	}

	AVLTree<K, V>& operator=(AVLTree<K, V> t)
	{
		swap(_root, t._root);
		return *this;
	}

	~AVLTree()
	{
		Destroy(_root);
		_root = nullptr;
	}

	bool Insert(const pair<K, V>& kv)
	{
		if (_root == nullptr)
		{
			_root = new Node(kv);
			return true;
		}

		Node* parent = nullptr;
		Node* cur = _root;
		while (cur)
		{
			if (cur->_kv.first < kv.first)
			{
				parent = cur;
				cur = cur->_right;
			}
			else if (cur->_kv.first > kv.first)
			{
				parent = cur;
				cur = cur->_left;
			}
			else
			{
				return false;
			}
		}

		cur = new Node(kv);
		if (parent->_kv.first < kv.first)
		{
			parent->_right = cur;
		}
		else
		{
			parent->_left = cur;
		}
		cur->_parent = parent;

		// 更新平衡因子
		while (parent)
		{
			if (cur == parent->_left)
				parent->_bf--;
			else
				parent->_bf++;

			if (parent->_bf == 0)
			{
				break;
			}
			else if (parent->_bf == 1 || parent->_bf == -1)
			{
				// 继续往上更新
				cur = parent;
				parent = parent->_parent;
			}
			else if (parent->_bf == 2 || parent->_bf == -2)
			{
				// 不平衡了，旋转处理
				if (parent->_bf == 2 && cur->_bf == 1)
				{
					RotateL(parent);
				}
				else if (parent->_bf == -2 && cur->_bf == -1)
				{
					RotateR(parent);
				}
				else if (parent->_bf == 2 && cur->_bf == -1)
				{
					RotateRL(parent);
				}
				else
				{
					RotateLR(parent);
				}

				break;
			}
			else
			{
				assert(false);
			}
		}

		return true;
	}

	Node* Find(const K& key)
	{
		Node* cur = _root;
		while (cur)
		{
			if (cur->_kv.first < key)
			{
				cur = cur->_right;
			}
			else if (cur->_kv.first > key)
			{
				cur = cur->_left;
			}
			else
			{
				return cur;
			}
		}

		return nullptr;
	}

	void InOrder()
	{
		_InOrder(_root);
		cout << endl;
	}

    bool IsBalanceTree()
    {
        return _IsBalanceTree(_root);
    }
    int Height()
    {
        return _Height(_root);
    }
private:
    int _Height(Node* root)
    {
        if(root == nullptr)
        {
            return 0;
        }
        int left_height = _Height(root->_left);
        int right_height = _Height(root->_right);
        return left_height > right_height ? left_height + 1 : right_height + 1;
    }

    bool _IsBalanceTree(Node* root)
    {
        // 空树也是AVL树
        if (nullptr == root) return true;

        // 计算root节点的平衡因子：即root左右子树的高度差
        int leftHeight = _Height(root->_left);
        int rightHeight = _Height(root->_right);
        int diff = rightHeight - leftHeight;

        // 如果计算出的平衡因子与root的平衡因子不相等，或者
        // root平衡因子的绝对值超过1，则一定不是AVL树
        if (abs(diff) >= 2)
        {
            cout << root->_kv.first << "高度差异常" << endl;
            return false;
        }
        if(root->_bf != diff)
        {
            cout << root->_kv.first << "平衡因子异常" << endl;
            return false;
        }
            

        // root的左和右如果都是AVL树，则该树一定是AVL树
        return _IsBalanceTree(root->_left) && _IsBalanceTree(root->_right);
    }

	void _InOrder(Node* root)
	{
		if (root == nullptr)
		{
			return;
		}

		_InOrder(root->_left);
		cout << root->_kv.first << ":" << root->_kv.second << endl;
		_InOrder(root->_right);
	}

	void RotateL(Node* parent)
	{
		_rotateNum++;
		Node* subR = parent->_right;
		Node* subRL = subR->_left;

		parent->_right = subRL;
		if(subRL)
			subRL->_parent = parent;

		Node* parentParent = parent->_parent;

		subR->_left = parent;
		parent->_parent = subR;
		
		if (parentParent == nullptr)
		{
			_root = subR;
			subR->_parent = nullptr;
		}
		else
		{
			if (parent == parentParent->_left)
			{
				parentParent->_left = subR;
			}
			else
			{
				parentParent->_right = subR;
			}

			subR->_parent = parentParent;
		}

		parent->_bf = subR->_bf = 0;
	}

	void  RotateR(Node* parent)
	{
		_rotateNum++;
		Node* subL = parent->_left;
		Node* subLR = subL->_right;

		parent->_left = subLR;
		if (subLR)
			subLR->_parent = parent;

		Node* parentParent = parent->_parent;

		subL->_right = parent;
		parent->_parent = subL;

		if (parentParent == nullptr)
		{
			_root = subL;
			subL->_parent = nullptr;
		}
		else
		{
			if (parent == parentParent->_left)
			{
				parentParent->_left = subL;
			}
			else
			{
				parentParent->_right = subL;
			}

			subL->_parent = parentParent;
		}
        parent->_bf = subL->_bf = 0;
	}

	void RotateRL(Node* parent)
	{
		Node* subR = parent->_right;
		Node* subRL = subR->_left;
		int bf = subRL->_bf;

		RotateR(parent->_right);
		RotateL(parent);

		if (bf == 0)
		{
			subR->_bf = 0;
			subRL->_bf = 0;
			parent->_bf = 0;
		}
		else if (bf == 1)
		{
			subR->_bf = 0;
			subRL->_bf = 0;
			parent->_bf = -1;
		}
		else if (bf == -1)
		{
			subR->_bf = 1;
			subRL->_bf = 0;
			parent->_bf = 0;
		}
		else
		{
			assert(false);
		}
	}

	void RotateLR(Node* parent)
	{
        Node* subL = parent->_left;
        Node* subLR = subL->_right;
        int bf = subLR->_bf;

		RotateL(parent->_left);
        RotateR(parent);

        if(bf == 0)
        {
            subL->_bf = 0;
            subLR->_bf = 0;
            parent->_bf = 0;
        }
        else if(bf == -1)
        {
            subL->_bf = 0;
            subLR->_bf = 0;
            parent->_bf = 1;
        }
        else if(bf == 1)
        {
            subL->_bf = -1;
            subLR->_bf = 0;
            parent->_bf = 0;
        }
        else
        {
            assert(false);
        }
	}

	void Destroy(Node* root)
	{
		if (root == nullptr)
			return;

		Destroy(root->_left);
		Destroy(root->_right);
		delete root;
	}

	Node* Copy(Node* root)
	{
		if (root == nullptr)
			return nullptr;

		Node* newRoot = new Node(root->_key, root->_value);
		newRoot->_left = Copy(root->_left);
		newRoot->_right = Copy(root->_right);

		return newRoot;
	}

private:
	Node* _root = nullptr;
public:
    int _rotateNum = 0;
};

void TestAVLTree()
{
	AVLTree<int, int> t;
	// int a[] = { 16, 3, 7, 11, 9, 26, 18, 14, 15 };
    int a[] = { 4, 2, 6, 1, 3, 5, 15, 7, 16, 14}; 
	for (auto e : a)
	{
		t.Insert({ e, e });
        cout << e << " -> " << t.IsBalanceTree() << endl;
	}

	t.InOrder();
    cout << t.IsBalanceTree() << endl;
}

void Test_AVLTree2()
{
	srand(time(0));
	const size_t N = 5000000;
	AVLTree<int, int> t;
	for (size_t i = 0; i < N; ++i)
	{
		size_t x = rand() + i;
		t.Insert(make_pair(x, x));
		//cout << t.IsBalance() << endl;
	}

	//t.Inorder();

	cout << t.IsBalanceTree() << endl;
	cout << t.Height() << endl;
}